This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-87922, filed Mar. 28, 2000; the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention is related generally to a computer graphics rendering system, method and program product for drawing a plurality of pixels in parallel.
2. Description of the Related Art
In the case where the display resolution is fixed, it is usual and inevitable to make use of the antialiasing technique, which is effective to minimize jaggies, in order to improve the quality of images. Super sampling is a technique for implementing the antialiasing technique.
In accordance with the super sampling technique, an object is drawn by a hardware at a resolution higher than the resolution of the display device followed by sampling appropriate pixels from the hardware drawn image and filtering the samples in order to reduce the resolution.
For example, in the case of displaying images for a screen having 320xc3x97240 pixels by super sampling at twice resolutions in the vertical and horizontal directions, after 640xc3x97480 subpixels are drawn at first, one pixel is generated by passing through an average filter each four subpixels thereof as a set arranged in a 2xc3x972 matrix as illustrated in FIG. 1, resulting in 320xc3x97240 pixels by repeating the filtering process for the respective blocks.
In other words, a number of subpixels are drawn on a main storage device such as a random access memory followed by reducing the resolution by means of a filter and displaying pixels on a display device such as a CRT.
However, in the case where the super sampling is performed at the resolution N times higher than the display resolution both in the horizontal direction and in the horizontal direction, there are problems that A) the memory space as required for drawing subpixels is N squared times the memory space for displaying final pixels and that B) the operation cost as required is N squared times the operation cost for displaying the same number of pixels.
Also, it is necessary to calculate a plurality of parameters for use in calculating R, G and B values and texture mapping and therefore to provide a number of multiply arithmetic circuits respectively for calculating these parameters, resulting in a larger hardware configuration as required.
In order to solve the shortcomings as described above, it is an object of the present invention to provide a high-quality and high-performance rendering system capable of super sampling only with a simple hardware configuration at a low cost.
In order to accomplish the above and other objects, a first aspect of the present invention resides in sampling pattern which is a combination of the relative position(s) of one or more sample point(s) in relation to the representative point; calculating parameters of an apex of a polygon and the gradient values of the parameters inside of the polygon; calculating the relative position of a representative point of a stamp in relation to the apex of the polygon; calculating the parameters of the representative point on the basis of the parameters of the apex of the polygon, the gradient values of the parameters inside of the polygon and the relative position of the representative point; and calculating the parameters of each sample point on the basis of the parameters of the representative point, the gradient values of the parameters and the relative positions of the each sample point.
The parameters include color information about the three primary colors of light (i.e., red, green and blue), the depth values (the Z values), the transparency values (A) and so forth.
The pixel is the irreducible element of an image which can be displayed by a display system. The values of parameters of a pixel are determined on the basis of the values of parameters of plurality of subpixels which are obtained by dividing the pixel. The sample points are subpixels which are used for determining the values of parameters of a pixel. The values of parameters of all the constituent subpixels are used for determining the values of parameters of a pixel in some cases while the values of parameters of only part of the constituent subpixels are used for determining the values of parameters of a pixel in other cases. In the case where the values of parameters of all the constituent subpixels are used for determining the values of parameters of a pixel, the sample points and the subpixels are equivalent to each other. However, in the case where the values of parameters of only part of the constituent subpixels are used for determining the values of parameters of a pixel, the sample points are particular ones of the constituent subpixels.
The sampling pattern contains the information about what subpixels are used for determining the values of parameters of a pixel. In other words, the sampling pattern is indicative of whether the values of parameters of all or part of the constituent subpixels are used, and indicative of what subpixels are used in the case where the values of parameters of only part of the constituent subpixels are used. More specifically speaking, the sampling pattern is a combination of the information items indicative of the relative positions of the respective subpixels in relation to a representative subpixel (called the representative point).
The polygon is the surface of a closed plane figure bounded by line segments and, in many cases, the surface of a triangular polygon having three apices. The apices of a polygon are the apices of the closed plane figure.
A stamp is a set of subpixels which can be drawn in one cycle.